// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <stddef.h>

#include <map>

#include "base/callback.h"
#include "base/files/file.h"
#include "base/memory/ref_counted_delete_on_sequence.h"
#include "base/memory/ref_counted_memory.h"

namespace content {

class DevToolsIOContext {
public:
    class Stream : public base::RefCountedDeleteOnSequence<Stream> {
    public:
        enum Status {
            StatusSuccess,
            StatusEOF,
            StatusFailure
        };

        using ReadCallback = base::Callback<
            void(const scoped_refptr<base::RefCountedString>& data, int status)>;

        void Read(off_t position, size_t max_size, ReadCallback callback);
        void Append(std::unique_ptr<std::string> data);
        const std::string& handle() const { return handle_; }

    private:
        Stream();
        ~Stream();
        friend class DevToolsIOContext;
        friend class base::RefCountedDeleteOnSequence<Stream>;
        friend class base::DeleteHelper<Stream>;

        void ReadOnFileThread(off_t pos, size_t max_size, ReadCallback callback);
        void AppendOnFileThread(std::unique_ptr<std::string> data);
        bool InitOnFileThreadIfNeeded();

        const std::string handle_;
        base::File file_;
        bool had_errors_;
        off_t last_read_pos_;
    };

    DevToolsIOContext();
    ~DevToolsIOContext();

    scoped_refptr<Stream> CreateTempFileBackedStream();
    scoped_refptr<Stream> GetByHandle(const std::string& handle);
    bool Close(const std::string& handle);
    void DiscardAllStreams();

private:
    using StreamsMap = std::map<std::string, scoped_refptr<Stream>>;
    StreamsMap streams_;
};

} // namespace content
